The operation of telephone networks (e.g. PSTN, Public Switched Telephone Network; PLMN, Public Land Mobile Network; ISDN, Integrated Services Digital Network) is based on telephone switching centers used for the transmission of calls. Therefore, it is of primary importance that the telephone switching centers should work properly. Telephone switching centers are complex systems, so maintaining their operational condition is a challenging task. One of the essential functions of a telephone switching center is to monitor its own operation and maintain statistics about it. However, it is to be noted that the various tasks relating to monitoring and statistics should not hamper the normal operation of the telephone switching system.
A large amount of data is continuously being collected about the operation of the telephone switching center. The data is collected e.g. by a network management system (NMS). The operation of the telephone switching system is monitored and managed by the network management system. From the data collected by the network management system, various statistics and reports are generated. Reports are generated e.g. about the calls transmitted by the telephone switching center. One of such reports is the Call Detailed Record (CDR) generated from a call. The call detailed record contains various call-specific data, including e.g. the parties to the call, call duration, etc. Reports are generated on the basis of various specifying functions. In this context, the ‘specifying function’ refers to a general denominator used to pick up a desired quantity from among the information collected for statistics. In the case of the call detailed record, this specifying function is called a counter. By using a counter, it is easy to pick up the desired quantities from the mass of information collected for statistics.
At present, a problem in the statistical and computing functions is that the information to be reported and the reports themselves are subject to changes. There may arise e.g. a situation where it would be desirable to add a new counter to the call detailed record. Currently the amount of work needed to add a single counter to an existing call detailed record is unreasonable.
Further, at present the network management system cannot be informed in real time as to what information is available from a given network element.